The changing profile of the patient undergoing coronary artery bypass surgery.

The first 100 consecutive patients undergoing isolated coronary artery bypass surgery in 1975 were evaluated with respect to the incidence of operative risk factors and outcome. When compared with an identically selected group from 1985, there was significant worsening of the preoperative condition over the decade with regard to mean age (p less than 0.0005), presence of congestive heart failure (p less than 0.05), left ventricular dysfunction (p less than 0.05), severity of coronary artery disease (p less than 0.001) and incidence of emergency operation (p less than 0.05). More patients in 1985 had associated medical diseases such as diabetes (p less than 0.01) and chronic lung disease (p less than 0.005). There was an increase in the occurrence of vascular diseases (hypertension, renal dysfunction, peripheral vascular and cerebrovascular disease) (p less than 0.05). Overall operative mortality increased from 1 to 8% (p less than 0.05) over the decade. Despite the deterioration in the clinical profile of the patient undergoing coronary bypass surgery, elective procedures were still performed with low mortality. The significant increase in overall mortality was chiefly in patients undergoing emergency operation (p less than 0.05). There were also increases in operative morbidity including low output syndrome (p less than 0.01) and respiratory (p less than 0.005) and neurologic (p = 0.06) complications.

Long-term results of myocardial revascularization.

During 1970 to 1977, among 1,733 patients who underwent isolated coronary bypass grafting, the operative mortality was 2.5 percent. Actuarial 5 year survival is 88.1 percent. At an average follow-up of 46 months (range 13 to 108), 90 percent of patients remain angina-free or with symptomatic improvement. The 5 year survival rate of patients with single vessel coronary artery disease is 97.9 percent. In patients with multivessel disease, operative survival appears to be favorably influenced by the presence of normal preoperative ventricular function. Late survival is significantly better in patients with multivessel disease with normal preoperative ventricular function or with complete revascularization. Risk of perioperative myocardial infarction has been appreciably reduced by the introduction of cold potassium chloride cardioplegia. Late myocardial infarction has occurred at an average annual risk of 1.46 percent. These data show that long-term survival and a small incidence of late myocardial infarction after myocardial revascularization are more likely in patients who undergo complete revascularization before significant left ventricular myocardial damage has occurred.

Exercise capacity during the first year after cardiac transplantation.

Few data are available examining the influence of perioperative clinical parameters on exercise capacity after cardiac transplantation. Accordingly, 40 patients were studied by metabolic exercise testing early (1 to 3 months) and late (6 to 12 months) after cardiac transplantation. Various clinical parameters, including congestive heart failure class, length of hospital stay, age, cold ischemic time and histologic evidence of rejection were correlated with exercise capacity after transplantation. As expected, peak exercise capacity correlated inversely with both age and length of hospital stay. There was no correlation with preoperative congestive heart failure class or heart rate at rest. Interestingly, there was a statistically significant correlation between cold ischemic time and exercise capacity after transplantation. In addition, increased episodes of rejection during the first 6 months after transplantation resulted in statistically lower exercise capacity at 6 to 12 months after the operation. Thus, ischemic damage during transport of the donor organs and subclinical damage during early rejection may affect clinical status after heart transplantation and may only be apparent during increased physical demand such as exercise.

Relation of silent myocardial ischemia after coronary artery bypass grafting to angiographic completeness of revascularization and long-term prognosis.

The prevalence and characteristics of silent myocardial ischemia as detected by 24-hour ambulatory electrocardiography ST-segment depression were prospectively assessed in 94 patients examined early (1 to 3 months) and 184 patients examined late (12 months) after coronary artery bypass grafting (CABG), and followed for a mean of 48 +/- 11 (range 4 to 62) months. The relation of ambulatory electrocardiographic silent ischemia to evidence of completeness of revascularization as defined by cardiac angiography performed 1 and 12 months after CABG, and to prognosis by follow-up of adverse clinical events was analyzed. Silent ischemia was detected early in 20% (19 of 94) and late in 27% (50 of 184) of patients, and showed a mean frequency of episodes ranging from 6 to 10 episodes/24 hours with a mean duration ranging from 15 to 23 minutes. The circadian distribution of episodes disclosed a significant peak of ischemic activity during the period of 6 A.M. to noon and a secondary peak between 6 P.M. and midnight (p less than 0.01 and p less than 0.001, respectively). Silent ischemia was not found by univariate analysis to be associated with graft or anastomotic site occlusions, low graft flow rates, grafted arteries with significant distal residual stenoses or ungrafted stenotic native coronary arteries. Kaplan-Meier analysis of time to cardiac event showed that silent ischemia was not predictive of an adverse clinical event in the early years after CABG. Cox regression analysis of 30 covariates only disclosed age (relative risk 1.06 [95% confidence interval, 1.01 to 2.94]) as having an effect on time to adverse clinical event.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary artery bypass surgery in patients aged 80 years or older.

Between August 1980 and January 1986, 23 patients aged 80 years or older underwent coronary artery bypass grafting (CABG) operations. These patients had a higher incidence of severe left main coronary artery narrowing (p less than 0.0001), 3-vessel coronary artery disease (p less than 0.05) and moderate to severe left ventricular dysfunction (p less than 0.05) than patients in the Coronary Artery Surgery Study registry older than 65 years. Of 14 patients undergoing elective simple CABG procedures, none died; of 19 elective cases overall, 2 patients died (11%). Three of 4 patients undergoing emergency procedures (75%) and 4 of 6 patients (67%) requiring intraaortic balloon counterpulsation died. Significant complications occurred in 9 of 18 survivors (50%). All operative survivors improved at least 1 New York Heart Association class, with a mean classification improvement of 3.7 to 1.6 (p less than 0.0001); 13 of 16 long-term survivors were in class I or II. Actuarial survival at 1 and 2 years is 94% and 82%, respectively. CABG can be performed electively in octogenarian patients with increased but acceptable mortality and morbidity risks. Functional improvement and long-term survival are excellent.

The Blalock-Taussig shunt in the first six months of life.

Because of increasing interest in the application of the Blalock-Taussig shunt in smaller infants, we reviewed the course of 18 infants aged 6 months or less who underwent this procedure. The mortality rate in 4 infants under 2 weeks of age was 50 per cent and that in those 2 weeks to 6 months of age, 28 per cent. The patency rate was 70 per cent. Because of late problems with the Waterston shunt and a comparable mortality rate, the Blalock-Taussig procedure is recommended for all infants, except perhaps those under 2 weeks of age.

In situ placement of a valved conduit at the pulmonary annulus.

The technique of repair of pulmonary atresia with intact ventricular septum is described. The porcine valved conduit (Hancock) was placed so that the valve was in the "anatomic" position, avoiding compression by the sternum. There was a mild gradient (15 mm. Hg) at a cardiac index of 4 L. per minute per square meter across the porcine valve itself, measured at the postoperative catheterization. The valve orifice diameter was only 15 mm., which is considerably less than the 22 mm. valve annulus. The possible merits of this procedure over the conventionally placed valved conduit and over an outflow tract patch are discussed.

Subclavian-coronary artery anastomosis in infancy for the Bland-White-Garland syndrome: a three-year and five-year follow-up.

Two infants, 4 months and 8 months of age, with anomalous origin of the left coronary artery, underwent direct anastomosis of the left subclavian artery to the left coronary artery. In the patient operated upon at 4 months of age, the anastomosis proved to be patent by angiographic study 3 years postoperatively. However, in the patient operated upon at 8 months of age, the study 5 years postoperatively revaled clinically unsuspected occlusion at the anastomosis site. After operation, both patients symptomatically improved. The heart size decreased on radiograms, the left ventricular ejection fraction improved, and the electrocardiographic abnormality resolved to a great extent. Since the preferred treatment for this abnormality and the ideal age for operation are yet to be established, long-term angiographic follow-up of all such surgically treated patients is needed. An advantage of the subclavian-coronary artery anastomosis is its applicability in the infant.

Myocardial injury and bypass grafting. Value of serum enzymes in diagnosis.

To clarify the value of serum enzymes in the detection of intraoperative and postoperative myocardial injury associated with coronary artery bypass grafting, we evaluated 70 consecutive patients (151 grafts). We used electrocardiograms and serial determinations of serum levels: serum glutamic oxaloacetic transaminase (SGOT), creatinine phosphokinase (CPK), lactic dehydrogenase (LDH), and LDH isoenzymes on Days zero, 1, 3, 5, 7, and 10. Patency of all grafts 1 week postoperatively was 92 per cent. Fourteen patients (20 per cent) had ECG evidence of acute myocardial infarction (AMI) or ischemia lasting longer than 48 hours. This incidence of AMI was attendant with no deaths or discernible changes in postoperative ventriculography. LDH-1 (cardiac fraction) was elevated in all patients with myocardial injury. Late elevation of LDH-1 occurred in 2 patients at the time of postoperative catheterization, 1 of whom had negative findings on ECG. Diagnostic correlation was not observed with total LDH, CPK, or SGOT. Predisposing factors to AMI included preinfarction angina (4 of 14 patients), occluded grafts (4 of 14), and a bypass time greater than 120 minutes.

Long-term effect of the superior vena cava-pulmonary artery anastomosis on pulmonary blood flow.

The long-term effects of the superior vena cava-pulmonary artery anastomosis were evaluated in 15 patients a mean of 8.5 years postoperatively. There were eight patients with tricuspid atresia and seven with other complex anomalies. Ten patients underwent 133xenon ventilation scans and 99mtechnetium perfusion scans in the upright and suprine positions. Perfusion scans showed decreased perfusion of the right upper lobe which improved in the supine position. Shunt flow, measured by thermodilution in nine patients, was a mean of 1.7 L. per minute per square meter, with a mean superior vena caval pressure of 8 mm. Hg and a resistance of 3.0 units. Right and left pulmonary venous saturations were 94 and 96 percent, respectively, showing little intrapulmonary shunting. Venous collaterals were the major cause for shunt failure. Six patients underwent a left Blalock-Taussig shunt and division of venous collaterals a mean of 6 years after the Glenn shunt and are all doing well. The superior vena cava-pulmonary artery anastomosis did not result in progressive pulmonary deterioration in the patients studied. The staged treatment of tricuspid atresia by the Glenn shunt followed by a systemic-pulmonary artery shunt and ligation of venous collaterals gives prolonged effective palliation.

The effects of cardiopulmonary bypass with crystalloid and colloid hemodilution on myocardial extravascular water.

The effect of cardiopulmonary bypass (CPB) on myocardial extravascular water (MEW) was evaluated with crystalloid and colloid hemodilution. Heart water was measured gravimetrically and by the double-indicator and thermal methods. CPB without hemodilution resulted in a 5.7 per cent increase in the wet : dry weight ratio of the left ventricle obtained by desiccation to stable weight. CPB with colloid hemodilution to a hematocrit of 10.7 +/- 0.4 per cent resulted in a 5.4 per cent increase in the wet:dry weight ratio. Crystalloid hemodilution to a hematocrit of 9.5 +/- 0.8 per cent resulted in a marked increase in myocardial water with a wet:dry weight ratio 30.3 per cent greater than the controls. Hypothermic (22 degrees C.) crystalloid hemodilution resulted in a 37.4 per cent increase in the wet:dry weight ratio. MEW was also measured by the double-indicator method with Evans blue dye and tritiated water. This method measured 85 per cent of the gravimetrically measured water. Although it indicated the increase in heart water in the crystalloid group, it proved less reliable in the measurement of MEW in this dynamic situation. The thermal heart water was also measured with an impedance and thermistor-bearing catheter similar to that used to measure thermal lung water. This proved ineffective in measuring heart water. Colloid hemodilution was thus found to prevent the development of myocardial edema which occurred with crystalloid hemodilution (p less than 0.01) with and without hypothermia. These findings support the addition of colloid to the hemodilution prime used for cardiopulmonary bypass.

Supraventricular tachyarrhythmias after myocardial revascularization: a randomized trial of prophylactic digitalization.

The success of prophylactic digitalization in reducing the incidence of supraventricular tachyarrhythmias (SVT) was studied in 140 randomly grouped, consecutive patients undergoing myocardial revascularization operations. The test group received either 1 or 1.5 mg. of digoxin the day before operation and were maintained postoperatively on 0.25 mg. of digoxin daily. There was a significant increase (p less than 0.05) in the incidence of SVT in the treated patients (17 of 61 or 27.8 percent) vs. the untreated patients (nine of 79 or 11.4 percent). There was no significant difference in SVT with the two digitalization dosage levels (31.6 percent with 1 mg. vs. 21.7 percent with 1.5 mg.). Prophylactic digitalization demonstrates no benefit in the prevention of SVT following myocardial revascularization and may, in fact, predispose the patient to these arrhythmias.

Left subclavian-left coronary artery anastomosis for anomalous origin of the left coronary artery. Long-term follow-up.

From 1972 to 1987, seven patients, from two to 28 months of age, underwent left subclavian artery-left coronary artery anastomosis for anomalous origin of the left coronary artery from the pulmonary trunk. All of these infants, median age 4 months, had severe congestive heart failure caused by anterolateral myocardial infarctions. There were two hospital deaths (29% mortality rate) with no late deaths after an average 10-year follow-up. All survivors have good exercise tolerance New York Heart Association class I), reduction in heart size, and significant improvement or normalization of ventricular function by echocardiography. Patency of the subclavian-left coronary artery anastomosis has been documented in two of four patients who have undergone catheterization. In contrast to other revascularizing procedures for treatment of an anomalous origin of the left coronary artery, anastomosis of the left subclavian to the left coronary artery may be performed without cardiopulmonary bypass or aortic occlusion. Moreover, this procedure appears to have an acceptable mortality rate with excellent long-term functional results in critically ill infants.

Follow-up of survivors of mechanical circulatory support.

Improvements in mechanical support for profound circulatory collapse have resulted in increasing survival of these critically ill patients. Since 1980, 27 patients aged 3 days to 69 years (mean 34.9 years) who required mechanical circulatory assistance have been followed up after discharge from the hospital. The refractory cardiogenic shock necessitating mechanical support occurred postoperatively in 22 patients (coronary artery bypass in nine, valve replacement in four, correction of congenital heart defects in nine) and with end-stage cardiomyopathy in five. Fourteen patients were supported with a Pierce-Donachy ventricular assist device (left ventricular assist in seven, right ventricular assist in three, both in four); nine were supported with extracorporeal membrane oxygenation, two with a Medtronic centrifugal left ventricular assist pump, one with biventricular Biomedicus pumps, and one with a Novacor left ventricular assist system. The duration of support ranged from 8 hours to 91 days with a mean of 3.5 days in patients supported for postoperative shock. Major complications occurred in 18 patients (67%), including bleeding that necessitated operative exploration in 14, serious infection in five, renal failure in two, and stroke in two. The five patients with cardiomyopathy underwent cardiac transplantation. The remaining 22 patients who had postoperative cardiogenic shock were weaned from support. There have been four late deaths: two cardiac related at 6 months and two of cancer at 46 and 53 months (one patient was in New York Heart Association class I and the other in class II before death). The remaining 23 survivors have been followed up for 3 to 79 months (mean 29 months) and at last examination 17 (74%) were in class I, two (9%) were in class II, three (13%) were in class III, and one (4%) was in class IV. Eight patients are employed full time, three are retired, four attend school, three are in preschool, one is a housewife, and one is unemployed but free of symptoms. Only four patients have significant cardiac disability, and one of these still works. In conclusion, mechanical circulatory assistance allows adequate support to permit satisfactory long-term survival in patients with refractory cardiogenic shock.

The rationale for operative therapy of symptomatic single-vessel coronary artery disease.

During an 8 year interval, 184 patients with symptomatic single-vessel disease underwent coronary artery bypass grafting (CABG). There were no operative deaths and only one late cardiac death (5 year cumulative survival 97.9%). At 48 months mean follow-up, 91% are angina free or improved. The low incidence of perioperative and late myocardial infarction (MI) and the preservation of ventricular function seen on follow-up catheterization suggest that coronary bypass operations yield significant benefits in severely symptomatic patients with single-vessel disease. Evidence is presented which supports the idea that single-vessel coronary artery disease may be a unique manifestation of coronary atherosclerosis and not one stage in a continuum.

Bypass grafts to the left anterior descending coronary artery: saphenous vein versus internal mammary artery.

During the interval 1972 to 1977, of 1,522 patients undergoing isolated coronary artery bypass grafting (CABG), 1,459 received grafts to the left anterior descending coronary artery (LAD). Internal mammary artery (IMA) was used in 765 patients and reversed saphenous vein graft (SVG) in 694 patients. Choice of bypass graft was nonrandom. Clinical follow-up is available in 98% of patients. Angiography has been obtained in 69% of eligible patients at 1 month, 65% at 1 year, 62% at 3 years, and 63% at 5 years. There was no difference in operative mortality rates (IMA 1.4%, SVG 1.9%) or 5 year actuarial survival rates (IMA 87.6%, SVG 88.7%). Graft flows were consistently higher at operation with the SVG, but patency rates at each interval were significantly higher with the IMA. Perioperative and late myocardial infarction occurred significantly less often in IMA patients. Superiority in IMA graft patency became apparent after an initial "learning curve" of 2 years of experience. Maintenance and/or restoration of normal left ventricular function was more common in IMA patients operated upon after the initial 2 year experience. IMA grafts are recommended for LAD bypass when the LAD is 2.0 mm in diameter or less. Early results with sequential SVG to the LAD suggest that this may be a realistic alternative to the IMA and may approach the 1 year IMA graft patency rate of 92.6%.

Aortic valve replacement. Aortic root versus coronary sinus perfusion with blood cardioplegic solution.

The role of retrograde coronary sinus cardioplegia in patients undergoing aortic valve replacement for aortic stenosis alone or in combination with myocardial revascularization has not been fully defined. Sixty-three patients undergoing elective aortic valve replacement received cold potassium blood cardioplegic solution via either the aortic root (36 patients) or the coronary sinus (27 patients). The patients were similar with respect to age, degree of aortic stenosis, ventricular function, severity of coronary artery disease, crossclamp time, completeness of revascularization, and mean volume and temperature of the infusion solution. The mean septal temperature and the release of myocardium-specific isoenzyme in the first 2 hours after crossclamp removal was higher in the retrograde group (p less than 0.008). Right and left ventricular function was preserved equally in the two groups, and volume-loading studies suggested improved diastolic performance in patients having retrograde cardioplegia. There were no differences between the two groups with respect to clinical outcome. We conclude that coronary sinus cardioplegia is as safe as aortic root perfusion for myocardial preservation in patients undergoing elective aortic valve replacement.

Aortic valve decalcification.

Ultrasonic decalcification of the aortic valve was performed in 22 elderly patients with critical aortic stenosis (aortic valve areas less than 0.8 cm2) as an alternative to prosthetic valve replacement. All of the patients had symptoms. The mean New York Heart Association class was 3.3 +/- 0.9. Adequate decalcification with restoration of leaflet mobility was achieved in all patients, including seven with bicuspid aortic valves. Leaflet perforation occurred and was successfully repaired in five patients. Ten patients underwent concomitant myocardial revascularization. There were two operative deaths (9%) and three late deaths. Echocardiograms were obtained preoperatively, postoperatively, and at 6 months. The mean aortic valve area increased significantly from 0.72 +/- 0.17 to 1.42 +/- 0.31 cm2 (p less than 0.001) and the peak gradient decreased from 74 +/- 34 to 25 +/- 13 mm Hg (p less than 0.001). At 6 months the aortic valve area (1.29 +/- 0.48 cm2) and peak gradient (31 +/- 12 mm Hg) continued to be significantly better than the preoperative measurements (p less than 0.001), but the 6-month aortic valve area was slightly decreased and the gradient increased when compared with the immediate postoperative values (p less than 0.02). The prevalence of mild to moderate aortic insufficiency increased from 50% of the patients preoperatively to 87% at 6 months (p less than 0.05). Two patients subsequently required aortic valve replacement for restenosis and aortic insufficiency. Ultrasonic decalcification is effective in relieving aortic stenosis, but subsequent restenosis and insufficiency may limit its application.

Intraaortic balloon pumping in patients requiring cardiac operations. Risk analysis and long-term follow-up.

The intraaortic balloon pump is usually the first mechanical device inserted for perioperative cardiac failure; however, little current information is available regarding short- and long-term effectiveness. From January 1983 through November 1990, 6856 adult patients underwent cardiac surgical procedures, 580 of whom (8.5%) had an intraaortic balloon inserted preoperatively (107 patients), intraoperatively (419 patients), or postoperatively (54 patients). There were 374 men and 206 women with a mean age of 63.9 years (range 19 to 88). Operations included 376 coronary artery bypass grafts, 100 mitral valve replacements (with or without bypass grafting), 70 aortic valve replacements (with or without bypass grafting), 15 double valve replacements (with or without bypass grafting), and 32 other procedures. There were 72 (12.4%) complications related to the balloon pump, of which 42 necessitated surgical intervention including thrombectomy (21), vascular repair (13), fasciotomy (2), aortic repair (1), and amputation (4). Operative mortality for patients supported by the balloon pump was 44%. Multivariate stepwise analysis of 27 parameters revealed six independent predictors of mortality: preoperative New York Heart Association class, transthoracic intraaortic balloon insertion (both p < 0.0001), preoperative administration of intravenous nitroglycerin, age, female gender, and preoperative balloon insertion (p < 0.001). Balloon-related complications were not predictive of death. Of the 326 hospital survivors, only 34 were lost to follow-up. There were 75 late deaths, the cause of which was cardiac in 41 (55%), noncardiac in 20 (27%), and unknown in 14 (19%). Actuarial survivals at 1, 5, and 9 years are 51%, 42%, and 33%. Of the 217 hospital survivors still alive and contacted, 81% were in class I (114) or II (60). These data demonstrate (1) operative mortality for patients requiring an intraaortic balloon in the perioperative period remains high, (2) perioperative risk factors can be identified, (3) complications related to the balloon pump do not affect survival, (4) operative survivors can achieve prolonged survival with excellent functional results, and (5) consideration for alternative methods of circulatory support is justified.

The effect of electrical vagal stimulation on canine pancreatic exocrine function.

The effect of electrical vagal stimulation on canine pancreatic exocrine function was studied in conscious dogs by stimulating intact thoracic vagus nerves, the distal ends of cut vagus nerves in animals with intact gastric denervation, and the distal ends of cut vagus nerves in dogs whose stomachs had been previously selectively denervated. The effectiveness of the stimulus was confirmed by monitoring gastric hydrogen ion output. The results indicate that stimulation of intact nerves produced minimal alteration in pancreatic output and bicarbonate and protein secretion while significantly increasing gastric fistula hydrogen ion output. Stimulation of the distal ends (efferent fibers) of cut vagus nerves in dogs with intact gastric innervation significantly increased the volume and protein output of the pancreas and the acid output of the stomach. Stimulation of the distal ends of cut right and both vagus nerves in dogs whose stomach had been denervated previously, again, significantly increased the volume and protein output of the pancreas without stimulation of stomach hydrogen ion output. The data presented in this study suggest that the canine pancreas is innervated directly by vagal fibers, which when stimulated produce an increase in protein (enzyme) output and volume of secretion. Maintenance of the pancreatic response following denervation of the stomach suggests that the response is primarily the result of direct vagal innervation and is not produced by gastrin released from the antrum.